This paper presents a general methodology for developing Nonlinear Low Order Model (NLLOM) from data collected from large detailed nonlinear models. This methodology is divided into two tasks: development of an Averag...
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We present a method for the synthesis of a control law which incorporates both a traditional linear output-feedback controller as well as a static anti-windup compensator. Unlike traditional anti-windup controller des...
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We present a method for the synthesis of a control law which incorporates both a traditional linear output-feedback controller as well as a static anti-windup compensator. Unlike traditional anti-windup controller design in which the linear controller and anti-windup compensator are designed sequentially, our method synthesizes all controller parameters simultaneously, thus providing a priori account of the effects of saturation on the closed-loop dynamics. Moreover, we derive sufficient conditions for the quadratic stability and (possibly) multiple performance bounds on the closed-loop dynamics such that the entire synthesis is cast as an optimization problem over linear matrix inequalitics (LMIs).
Several Kalman filter designs were developed and tested for controlling a spray etching process. A hybrid extended Kalman filter was found to yield biased estimates in the presence of process-model mismatch. This issu...
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This paper presents a general methodology for the development of Nonlinear Low Order Models (NLLOM) from data collected from detailed nonlinear simulation models. This methodology is divided into two tasks: developmen...
This paper presents a general methodology for the development of Nonlinear Low Order Models (NLLOM) from data collected from detailed nonlinear simulation models. This methodology is divided into two tasks: development of a Average Linear Low Order Model (ALLOM) and augmentation of the ALLOM to form a NLLOM, the latter task being the focus of this paper. The tools examined for the nonlinear augmentation of the ALLOM include stepwise regression and nonlinear optimization. Results will be presented for the application of these techniques towards the development of an NLLOM from a detailed high purity distillation simulation.
A steady state, multivariable, and nonlinear measure is presented for assessing the input-output, open-loop controllability of a process. This measure is ascertaining the inherent controllability of the process, as it...
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A steady state, multivariable, and nonlinear measure is presented for assessing the input-output, open-loop controllability of a process. This measure is ascertaining the inherent controllability of the process, as it is calculated in the absence of any regulatory control structure. It is also independent of the inventory control structure that might be assumed present in order to keep the inventory levels constant. This measure evaluates the ability of a design to reach all points of the desired output space and to reject the expected disturbances utilizing input action not exceeding the available input space. Besides being applicable to a SISO case, its multivariable character is shown to be more accurate than existing measures such as RGA, minimum singular value, and condition number.
A new input signal design method is proposed for constrained multivariable systems that aims to maximize the signal to noise ratio while also meeting certain input and output constraints. The proposed methodology util...
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A new input signal design method is proposed for constrained multivariable systems that aims to maximize the signal to noise ratio while also meeting certain input and output constraints. The proposed methodology utilizes an approximate steady state model that is assumed to be known a-priori. The steady state operability concepts are used to incorporate the steady state input and output constraints into the signal design. The input test signal design problem is formulated as a nonlinear optimization problem and it is shown that all the existing methods can be unified under this proposed design framework. It will be proven that the design method is D-optimal from a steady state perspective. For ill-conditioned systems, more energy will be automatically directed in the weak directions. An example will be given to demonstrate the superiority of the method.
The objective of this paper is to explore the application of wavelets to the field of data compression in the process industry. The wavelet transform is compared with the discrete Fourier and cosine transforms. To exa...
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The objective of this paper is to explore the application of wavelets to the field of data compression in the process industry. The wavelet transform is compared with the discrete Fourier and cosine transforms. To examine a complete approach to data compression, quantization techniques are applied to the transformed coefficients. Different quantiser designs are used for the compression of data from an industrial distillation column. Comparisons are made with the Box-Car and backward-slope methods currently used in the process industries.
Despite recent advances in the field, the tuning of presently popular Model Predictive control formulations is largely a trial and error procedure. Motivated by this fact, a Reference System based tuning is explored t...
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Despite recent advances in the field, the tuning of presently popular Model Predictive control formulations is largely a trial and error procedure. Motivated by this fact, a Reference System based tuning is explored through Reference System Model Predictive control. The RS-MPC algorithm is examined because of its potentially more intuitive approach to tuning. Under this methodology the tuning involves the selection of two parameters for each controlled variable. The first parameter adjusts the shape of the response and the second one affects the speed. Using these, instead of the weight-based tuning of conventional MPC, much of the trial and error is eliminated. The most important features of the controller arc elucidated through the performance of the STSO and MIMO cases for the Amoco Fluid Catalytic Cracker process simulation.
We present a stabilizing scheduled output feedback Model Predictive control (MPC) algorithm for constrained nonlinear systems with large operating regions. We design a set of local output feedback predictive controlle...
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We present a stabilizing scheduled output feedback Model Predictive control (MPC) algorithm for constrained nonlinear systems with large operating regions. We design a set of local output feedback predictive controllers with their estimated regions of stability covering the desired operating region, and implement them as a single scheduled output feedback MPC which on-line switches between the set of local controllers and achieves nonliilear transitions with guaranteed stability. This algorithm provides a general framework for scheduled output feedback MPC design.
Static principal component analysis (PCA) statistical charts are used to assess and compare the performance of two plant-wide control strategies of the Tennessee Eastman process. Both centralized and decentralized cha...
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Static principal component analysis (PCA) statistical charts are used to assess and compare the performance of two plant-wide control strategies of the Tennessee Eastman process. Both centralized and decentralized charts are used as well as charts relating to the energy and material balance of the process. In most cases these charts reveal the origin of the disturbance and the effectiveness of the control structure to compensate for the disturbance. Differences and similarities between the two control structures are also examined.
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